1. Technical Field of the Invention
The present invention is directed to a top comb for a combing machine comprising at least one row of stamped needles that are arranged in a parallel side-by-side relation and enclosed between two cover plates with a free needle projection being left free, wherein compressed air channels are formed between the cover plates and adjacent pairs of needles. A top comb of this type is known from EP 0 351 443 C1.
2. Prior Art
During the combing process particles and fiber residue deposit on the free needle projection that interfere with the combing quality. To counter these deposits, mechanical cleaning devices were initially used. A significant improvement was attained with a pneumatic cleaning of the needle projection, as it is described in EP 0 351 443 C1.
With this as the starting point, the invention is based on the object of further increasing the effectiveness of the cleaning effect in a pneumatically cleaned top comb of the above type.
This object is met according to the invention in such a way that the needles have embossings such that the congruent embossings of adjacent needles form an air channel and the embossings narrow in their widths toward the outlet area.
Due to this narrowing and, hence, reduction in cross section, an increase is attained in the flow velocity of the exiting airflow, so that the same can be used even more effectively for cleaning. Furthermore, the airflow can also be directed even more specifically toward those sections of the free needle projection where particularly heavy impurities are deposited.
In a further design of the invention, provision is made for at least one cover plate to have a free projection in the outlet area and to be bent inward under formation of an air conducting zone. This supports the targeted guiding of the airflow.
Provision may furthermore advantageously be made for the embossings in the needles to extend into the region of the free needle projection. This provides for a certain guiding of the airflow even after it has left the zone that is covered by the cover plates.
The cover plates advantageously project beyond the needles at their top sides and an air supply channel and/or an air distribution channel is formed in this region by means of a deep-drawing of the cover plates. In this manner, the compressed air coming from a compressed air source can be distributed to the channels that are formed between the individual needles.
Lastly, provision may be made for an airflow divider to be formed in the air channel. This creates two partial airflows that can be directed specifically, for example, toward the front edge and the rear edge of the needle.